The purpose of this longitudinal proposal is to continue the investigation of a near total county population of white male elementary school children (N equals 497) who were administered a developmental- neuropsychological test battery at the beginning of kindergarten (Fall, 1970) and a cross-validation sample of similar children (N equals 181) who were tested at the beginning of kindergarten (Fall, 1971). Because of active cooperation and participation of the county school system, virtually all of the original standardization and cross-validation groups (96%) are still involved in the project. The general purposes of the project are threefold: (1) to evaluate the predictive validity and utility of the test variables, given in 1970, against the current reading achievement criteria (Early Detection Problem), (2) to determine whether performance on these developmental measures changes differentially as the disabled and average readers become older (Developmental Lag Problem) and (3) to determine the relationship, if any, between specific reading disability and precursors more remote in time (e.g., neurological birth status and familial reading problems). The objectives outlined for the sixth year of the project regarding investigation of the preceding problems include: (1) Year 4 and Year 5 reading criteria determinations for the cross-validation and standardization samples, respectively; (2) collection of family reading, birth history, and neurological data on experimental and matched control subjects in the cross-validation sample, and analyses of differences in these data between groups in both samples and (3) second readministration of the original test battery to the experimental and control subjects obtained from the standardization population.